Medical procedures such as laparoscopy and the like, which employ a tip at the end of a tube for insertion into the patient, are beneficial because the incisions necessary to perform them are minimal in size, therefore promoting more rapid recovery and lower costs. For example, a patient who undergoes laparoscopic surgery may typically return to normal activity within a period of a few days to about a week, in contrast to more invasive procedures requiring a relatively larger incision (which may require about a month for recovery). (Although the term “laparoscopic” is typically used hereinafter, such use of the term “laparoscopic” should be understood to encompass any such similar or related procedures such as, for example, arthroscopic, endoscopic, pelvoscopic and/or thoroscopic or the like, in which relatively small incisions are used.)
Medical devices used in laparoscopic procedures typically include a handle or other actuation assembly, which is connected to a tube that extends from a proximal end near the actuation assembly to distal end of the tube, and the tube includes an inner shaft which also leads from the proximal end of the tube to the distal end of the tube. A tool-bearing tip is typically attached to the distal end of the tube and inner shaft, and the tool may be actuated—for example, if the tool includes shears, the blades of the shears may be opened and/or closed—by differential movement of the inner shaft relative to the tube.
In some laparoscopic medical devices, the tip (which typically includes a back hub for connection to the tube and a yoke for connection to the inner shaft) is attached to the tube and inner shaft by threading, and the correct operation of the tool depends on precise machining of two sets of threading—the first threading for connecting the tube to the tip, and the second threading for connecting the yoke of the tip to the inner shaft of the medical device (in which the first and second threadings may be of mutually different pitches, respectively; or, alternatively, of the same pitch). However, in some such implementations, the allowable assembled tolerance may be on the order of ±0.0015 inches for the distance between the tube end threading and the inner shaft threading when assembled with a pin, for example.
Such narrow tolerances often require intricate machining and manufacturing when making the medical devices and tips, and during production assemblers may often be required to repeatedly iterative processes—including multiple machining and testing steps—to make the fine adjustments necessary for the manufactured medical devices to function properly. This can lead to substantially increased production times and costs.